1. A. is spherical and remains centered on the spaceship as it moves.
Q37.1
As a high-speed spaceship flies past you at half the speed of light, it fires a strobe light. An observer on board the spaceship measures a spherical wave front that spreads away from the strobe light with the same speed c in all directions. The wave front that you measure
A. is spherical and remains centered on the spaceship as it moves.
B. is spherical and is centered on the point where the spaceship was when the strobe was fired.
C. is not spherical but remains centered on the spaceship as it moves.
D. is not spherical but is centered on the point where the spaceship was when the strobe was fired.
Answer: B

2. A37.1
As a high-speed spaceship flies past you at half the speed of light, it fires a strobe light. An observer on board the spaceship measures a spherical wave front that spreads away from the strobe light with the same speed c in all directions. The wave front that you measure
A. is spherical and remains centered on the spaceship as it moves.
B. is spherical and is centered on the point where the spaceship was when the strobe was fired.
C. is not spherical but remains centered on the spaceship as it moves.
D. is not spherical but is centered on the point where the spaceship was when the strobe was fired.

3. A. reaches point A before it reaches point B.
Q37.2
As a high-speed spaceship flies past you at half the speed of light, a strobe light fires at the center of a room aboard the spaceship. As measured by you, the light from the strobe
A. reaches point A before it reaches point B.
B. reaches point B before it reaches point A.
C. reaches points A and B simultaneously.
D. not enough information given to decide
Answer: B

4. A37.2
As a high-speed spaceship flies past you at half the speed of light, a strobe light fires at the center of a room aboard the spaceship. As measured by you, the light from the strobe
A. reaches point A before it reaches point B.
B. reaches point B before it reaches point A.
C. reaches points A and B simultaneously.
D. not enough information given to decide

5. D. The answer depends on the speed of the train.
Q37.3
A high-speed train is traveling from Capital City to Shelbyville. According to an observer at rest on the ground, the clocks at the railroad stations in Capital City and Shelbyville both strike noon at the same time.
According to a passenger on the train, when the Capital City clock strikes noon, what time is it in Shelbyville?
A. noon
B. before noon
C. after noon
D. The answer depends on the speed of the train.
Answer: C

6. A37.3
A high-speed train is traveling from Capital City to Shelbyville. According to an observer at rest on the ground, the clocks at the railroad stations in Capital City and Shelbyville both strike noon at the same time.
According to a passenger on the train, when the Capital City clock strikes noon, what time is it in Shelbyville?
A. noon
B. before noon
C. after noon
D. The answer depends on the speed of the train.

7. Q37.4
Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship.
According to Maria, at the instant that Samir’s stopwatch reads 16.0 s, Maria’s stopwatch reads 20.0 s.
According to Samir, at the instant that Maria’s stopwatch reads 20.0 s, Samir’s stopwatch reads
A s.
B s.
C s.
D. none of the above
Answer: C

8. A37.4
Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship.
According to Maria, at the instant that Samir’s stopwatch reads 16.0 s, Maria’s stopwatch reads 20.0 s.
According to Samir, at the instant that Maria’s stopwatch reads 20.0 s, Samir’s stopwatch reads
A s.
B s.
C s.
D. none of the above

9. Q37.5
Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship.
According to Maria, at the instant that Samir’s stopwatch reads 8.0 s, Maria’s stopwatch reads 10.0 s.
According to Maria, her spaceship is 100 m long (along the direction of motion). According to Samir, the length of Maria’s spaceship is
64 m.
80 m.
C. 100 m.
D. 125 m.
E. none of the above
Answer: B

10. A37.5
Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship.
According to Maria, at the instant that Samir’s stopwatch reads 8.0 s, Maria’s stopwatch reads 10.0 s.
According to Maria, her spaceship is 100 m long (along the direction of motion). According to Samir, the length of Maria’s spaceship is
64 m.
80 m.
C. 100 m.
D. 125 m.
E. none of the above

11. According to Santiago, the speed of the rocket is
Q37.6
Santiago stands on the ground as Miriam flies directly toward him in her spaceship at 0.5c. She fires a small rocket directly toward Santiago that flies at a speed of 0.8c relative to her spaceship.
According to Santiago, the speed of the rocket is
A. 1.3c.
B. faster than c but slower than 1.3c.
C. c.
D. faster than 0.8c but slower than c.
E. 0.8c.
Answer: D

12. A37.6
Santiago stands on the ground as Miriam flies directly toward him in her spaceship at 0.5c. She fires a small rocket directly toward Santiago that flies at a speed of 0.8c relative to her spaceship.
According to Santiago, the speed of the rocket is
A. 1.3c.
B. faster than c but slower than 1.3c.
C. c.
D. faster than 0.8c but slower than c.
E. 0.8c.

13. A. increases by a factor greater than 2.
Q37.7
According to the relativistic expression for momentum, if the speed of an object is doubled, the magnitude of its momentum
A. increases by a factor greater than 2.
B. increases by a factor of 2.
C. increases by a factor greater than 1 but less than 2.
D. depends on the value of the initial speed.
Answer: A

14. A37.7
According to the relativistic expression for momentum, if the speed of an object is doubled, the magnitude of its momentum
A. increases by a factor greater than 2.
B. increases by a factor of 2.
C. increases by a factor greater than 1 but less than 2.
D. depends on the value of the initial speed.

15. D. depends on the value of the speed.
Q37.8
According to the relativistic expression for kinetic energy, the kinetic energy of an object of mass m moving with speed v
A. is equal to (1/2)mv2.
B. is less than (1/2)mv2.
C. is greater than (1/2)mv2.
D. depends on the value of the speed.
Answer: C

16. A37.8
According to the relativistic expression for kinetic energy, the kinetic energy of an object of mass m moving with speed v
A. is equal to (1/2)mv2.
B. is less than (1/2)mv2.
C. is greater than (1/2)mv2.
D. depends on the value of the speed.